Conveyance technology for conveying material for optical elements such as a lens to a forming die by contact-adsorption using an adsorbing pad structured by Teflon (TM) or heat-resistant gum, etc., provided in a conveyance arm is known. The optical element material is heated and softened by a heating device, such as an infrared lamp provided around the forming die. The adsorbing pad is arranged to adsorb a formed optical element for collection after formation.
A forming time can be shortened if the optical element material is heated while it is conveyed. However, it is necessary to covey melting optical element material. Consequently, there is a problem that conveyance is difficult with abovementioned contact adsorption system. Further, in the case of conveying melting optical element material by putting it on a conveyance member equipped with a heater, it is necessary to have a conveyance member having anti-melting device thereon. Further, there is a problem that heating unevenness tends to occur with it. To solve this problem, Japanese Patent Application Open to public No. 2004-51291 discloses technology capable of conveying optical element material with a non-contact state.
According to the technology-disclosed in Japanese Patent Application Open to Public No. 2004-51291, it is possible to hold optical element material in a floating state by blowing high-speed air from the bottom of a supporting apparatus having a funnel shape. However, there is a problem that since the conveyance apparatus includes an electric heater to heat air, electric heater life tends to be rapidly shortened resulting in breaking wire when the temperature of the heater is high, such as 1000° C. Since magnesium oxide powder used for insulation of nichrome wire for the electric heater rapidly starts dielectric breakdown, when temperature reaches more than 900° C., the nichrome wire tends to be short cut. Accordingly, it reduces the operating rate of a conveyance apparatus. Further, it is necessary to pay attention to the safety of a conveyance apparatus and it is difficult to handle with the conveyance apparatus. Even though a case such as the sheath of an electric heater is structured by incoloy 600, etc., which is heat-resisting alloy, it is easily oxidized and blackened, when temperature is more than 700° C. As a result, there is a problem that phenomenon that the surface of the case comes off occurs and foreign matters tend to be generated. In the case of a heating system using gas, once a foreign matter is generated, the foreign matter get into the gas flow and there is a possibility that the foreign matter is easily conveyed to a heating object and adheres on the heating object. Since the foreign matter systematically pollutes the heating object, which is going to be a big problem, every efforts should be made to avoid this implementation. Particularly, a fine structure being a sub-micron order structure is formed on the surface of an optical element for an optical pickup apparatus. Accordingly, if foreign matter adheres on nitric material and the optical transcription surface of an optical element forming die, there is a possibility that the optical characteristics of a formed optical element deteriorates.